1. Technical Field
The present invention relates to a wave gear device, and more particularly to a sealed-type wave gear device appropriate for being used as a drive mechanism in a clean room and the like.
2. Description of the Related Art
There have been known wave gear devices provided with a flexible external gear having a shape of ring or a, cup or a silk hat. For example, the inventors of the present invention disclosed a wave gear device of the type having a flexible external gear in order to shorten the axial size of the device in Japanese Patent application Nos. HEI 6-310834 and HEI 6-310835, both assigned to the same assignee of the present invention.
The inventors of the present invention also disclosed a flat wave gear device constituted to have a structure suitable for adopting the aforementioned flexible external gear in Japanese Patent Application No. HEI 7-120957, assigned to the same assignee of the present invention.